The present invention relates to a touch panel controller which produces detection data according to whether a touch panel detection plane is touched or not, and a technique useful in application to a one-chip controller integrated circuit (IC) having e.g. a touch panel controller, a display driver and a processor.
In touch detection according to a mutual capacitance method, one of an array of X-electrodes and an array of Y-electrodes, which are arranged to intersect with each other, is used as an array of drive electrodes, and the other is used as an array of detection electrodes; while the drive electrodes are selected and driven sequentially, detection data are taken at intersection positions where each drive electrode selected and driven intersects with the detection electrodes. In touch detection according to a self capacitance method, detection data according to touch or no touch are acquired by performing charge transfer on each electrode of X-electrodes and Y-electrodes, which are arranged to intersect with each other. Either of the detection methods needs a detection circuit for touch detection which performs detection by capturing signals arising on detection electrodes in units of the detection electrodes. Each detection circuit takes signal charges according to touch or no touch by using an integration circuit, a switched capacitor circuit or the like to perform a switched capacitor operation.
There has been known a technique for reducing the power consumed by an operation for such touch detection. According to the technique, a touch panel is arranged so that a determination about a touch input is enabled by just monitoring a receive level arising on a particular detection electrode; and the touch panel has an intermittent detection mode in which only the receive level arising on the particular detection electrode is detected at intervals of a fixed length of time for a waiting time of the touch panel waiting for an input operation. According to the arrangement like this, when detecting a touch input, the touch panel transitions to a detection mode. In the detection mode, all of circuits are activated to detect a position subjected to the input operation, whereby the power consumption during the waiting time can be reduced.
The patent document, JP-A-2013-206296 discloses an example of the technique for reducing a power consumed by an operation for touch detection.